Blacksmithing - making a small crucible 

Found a great source of wild clay and am thinking about making a crucible with it. You've got my gears turning, thanks for posting!

Very interesting. I liked following your thinking. Couple of things - plaster will work for a single firing. Similar to what is done with lost wax casting. For a reusable crucible, not a good product. Forget using sand. You aren't making cement; you are making a ceramic. Smooth interior is preferable. Firebrick is a good idea. Clay can be harvested from the nearest stream, or you can use some old original cat litter. It was clay and would be quite usable here. Buy or make a ball mill - the kind they polish rocks with. Let the ingredients tumble for a few hours. You will end up with a very fine powder, almost like talc. This is what you want. All forms need to be surface sealed and treated with a release agent. Too much moisture is just as much a problem as too little, but even more important is slowly drying. Keep covered with a damp cloth, and keep the cloth moist. 3 to 7 days. Then fire it. Ceramics need to cool down slowly from the initial firing. Several hours of gradual decreasing temperature. Should be fine after that. Forget using steel or cast iron. You will burn a hole in these very quickly. And while it is certainly easier to just buy a crucible, I love seeing people trying to relearn old skills. Keep up the good work.

Glen, your mixtures seemed to be too wet. You only need enough water to moisten to the point that when squeezed in your hand, it will stay in one lump. It should not be pourable. Try a paper cup. Press in the floor first, then cut up an Al beverage can and make a circular form using tape on the inside of the circular form. Then press the walls in using a dowel or something to lightly tamp it down around the form. Using the taped Al and paper cup makes it easy to extract. Or, just use a thick walled steel cup (piece of pipe with bottom welded on) to melt the copper. I really like your experimentation videos. Thanks, Jerry

I like the fact you’re not afraid to show your failures. I’m really looking forward to where you’re going with this. Nice job Glen.

You know, that by taking a dense, non insulating fire brick (from a wood stove liner) and cutting a pocket in it will work. Also drill a couple of holes from side to side on either side of the crucible to insert rods to use as removable handles. Sorry it took me so long to watch this video. Keep up the good work. Your experimenting has saved me a lot of time and frustration.

plaster of paris will serve as better binder than portland cement, beside you can pull it off the mold before it completely dry, so risk of mold destruction can be avoided.. also try to use talcum powder as source of alumina and magnesia, its much cheaper than crushed firebrick, and last use waterglass (sodium silicate/ diluted sodium) as the high temp glue.. all this work fine if you can't acces graphite and bentonite to make crucible

Excellent! Hi Glenn. Dry clay. Unfired. With your old red clay brick or fire brick crushed. Alittle water. Make small Pinch pot. Cement is not as 'temperature- safe" as real ceramic aka high fire ceramic clays. Say 3000f. Copper melts at 2000f. Cement is not a ceramic. Love this new direction you are taking us! Thank you

Nice to watch the thought process, thanks for bringing us along for the ride on your learning curve 😁👍🤘

Try vermiculite, a traditional refractory material and available at garden supply stores. Water glass (sodium silicate) and sand is also used at high temperatures as a matrix. These 3 together might work . . . maybe.

Total respect for the experimentation. Well done on your efforts.

Pretty cool Glen, you’re a DIY scientist man. You try,fail,try,fail, and then succeed! Love it man!

Thanks for posting this Glen and many thanks to the others who added their thoughts. Like you I like experimenting and figuring things out for myself - even if it is far more practical just to purchase the commercial product :-) Cheers! Hank

That was so educational Glenn, I just love your experimental approach using the stuff that most of us can get our hands on. Cheers!

Just finished my first crucible only I made mine out of stone,it works awesome and holds hear very well. No noticable damage from the firing and I got it red hot! It the ancient method but my crucibles will outlast modern ones by a billion years or so. Lol

Just finished my first crucible only I made mine out of stone,it works awesome and holds hear very well. No noticable damage from the firing and I got it red hot!

Interesting, would have bet my arse it would fail but you proved my wrong! Good job Glen!

White stoneware clay powder with high alumina content, Graphite powder, Crushed up flint or other high temp stoneware ceramic mixed in, and then silica carbide powder.. mix em into a clay rather, form it and fire it - slowly... Cement will always break down under high heat.. thus you rarely find cement in commercial grade lining materials.

Interesting video Glenn. Look forward to your next attempts. Thanks for the video.

Excellent and an Honest job....you sir really are a Grandmaster.

Hi Glenn!still loving my tongs and touchmark! BTW cheap cat litter is pure bentonite clay and easily dissolves in water.many use this in home made refractory cement

Glen wrap your word or what ever you are going to use for the void with some plastic wrap of some kind this way you can pull out the wood very good easy and burn out the plastic if it stays. Great video as always. Martin

Also, Glen the carved out wood stove firebrick will catch the flux when welding thus preserving your forge liner.

Fan for life. Thank you Glen

Nice attempt! Look forward to your next trial.

If you were willing to sacrifice a cup just leave everything together and put it in your forge.

I never thought about it being the MacGyver method using whatever we had lying around, but that is a good analogy. that deep in the back of my head probably had influence on some of the projects my friend and I have done over the last coupe of years. Interesting project you have going on as well. Pretty nice to see.

great job, I love the creativity and willingness to try things for yourself. we share that child-like curiosity. awesome! roger

Commercial crucibles are made from clay. There is no cement in them. Cementation occurs when the crucible is baked or fired at high temperatures. Crucibles are more of a ceramic like porcelain.

For the second crucible i recommend you let it dry for at least 2 days

I like your try and error method 👍

I'm binge watching today, great videos

You should use castable refractory cement with firebrick as a stretcher.

When using concrete and metal. If you dont want the metal to stick to the concrete. We used a method when I was making sewer lines. Get used motor oil and mix some diesel fuel with it (3 parts oil, 1 part diesel). Dip the metal into this mixture (whatever parts will be touching the concrete) and the metal can slide out when its dry. Also may be a good idea to let it cure for 12 to 24 hours. Just to make sure the concrete isnt moist at the end

Your problem is your binding agent. Cement is primarily made from lime. Lime when heated to high heat breaks down. Actually if you put a lime stone in a fire and then pour water over it after it has cooled it will break apart just like your third try did. It is actually how cement is made. A sodium silicate mixture as your binding agent would work much better. To make sodium silicate you need water, 100% lye (stump remover), and silica gel (found in desicate packs. Check at your local motorcycle dealer they sometimes have big packs of them from the shipping process.) If you search Google you should be able to find a recipe. Mix that in place of water with something like your fire brick and it should work you could also try perlite (garden stores carry it.), Or clay instead of fire brick.

a very interesting experiment, certainly useful, tnx 👍

For melting copper I use stainless I made a cup from 50mm pipe 3mm wall about 50mm deep and it works perfectly and forever reusable

Hey, Thank you sincerely for giving me an idea Sir to save income & time !

A tip is dry the cement very slowly, for it to add a little bit sugar in the water to mix with cement. Increase the heat resistance when the cement dry slowly.

try changing the cement to Calcium dioxide and add a little bit of sugar, here in South-Brazil when we do clay ovens or something like that we add sugar in the composition of the clay, in order to avoid cracks

The wood needs to soak to expand beforehand, and a vasilene release is a good idea.

I've not finished the video yet. However I think instead of sand I would use something with a higher flashpoint. Like glass, glass is a superheated form of fine grain sand. So it's flashpoint is understandably higher, also I wouldn't worry about removing the crucible from the cup at all. If it wants to separate it's going to during the heat treatment directly after the casting of the crucible. Remember to allow it to cool gradually. Don't let it lose temperature too quickly... Anyway I don't know a damn thing about the chemistry of a crucible but I do fully understand thermo dynamics. You really need a gas oven to do this. Also if you aerated the concrete it becomes less likely to crack.

Whatever you used to make your own spray and Pam or coated in diesel fuel what they call form release that keeps the concrete or whatever else you're using your bowl from sticking

Amazing

So if you only want to melt copper , I suggest you can use sardines can as your crucible , don't burden yourself

Nice job my guy

You should not use regular cement for a crucible, it has too much moisture in it. It also soaks up water. The problems begin when you heat it up. The regular cement will explode if there is any moisture in it when it is heated.

Thank you Glen. I love your videos. You are in my opinion one of the better youtube smiths. Would you mind posting in the comments the ingredients, ratios and specific steps you used for the successful crucible, along with any comments on what you might do differently? -Vikingsmith, Yakima, WA, USA

Will Thai work or not " psh idk! " Lmao loved it being as real as possible! Definitely Clicked subscribed lmfao

If using wood dowels, use Vaseline to coat wood. May help. Never done it before.

A couple of quick thoughts, Portland cement useless for heat better to use high alumina cement. No sand. Mixture way too wet needs to be just damp enough to pack into place. Allow some (many) days for cure - keep damp for that time. Dry slowly before firing. Don't use wooden formers as they expand with moisture and can crack part use plastic instead. But my main suggestion is go out and buy a proper clay/graphite crucible they are not that expensive...... Martin

Melt borax inside the crucible. You need it all over the inside. That way the molten metal won't stick👍

Failure is the best teacher. Petroleum jelly or talc is a good mold release. Try plaster of paris instead of cement.

Fire brick is a bad conductor of heat wasting gas, Use clay 40% and Graphite 60% powder and sodium silicate as binder. best part of it, it`s recyclable, play with recipe, like your work man.

Cement needs to setup for 30 days and to get best strength keep it wet! Wood does absorb water causing cement to split! Because cement has a adhesive bond and can't be disturbed or dropped on counter to hard! Best to Ya!

Wonder If "graphite pencil as a composit" will it work to make graphite crucible mold

Replace the concrete in your recipe with plaster and see how that works.

You can grind granite finely and mix it in equal quantities with cement or plaster. Try and see

Part of the problem is that the mixture is too wet. I can't tell from the video, but it looks like the right consistency @ 10:02...before you added more water. 1.) If there's too much moisture then the casting will take longer to cure before you can risk firing it. 2.) When you place what you want for an inner diameter, make sure the crucible as a whole will have at least 1/2 inch wall thickness. {Basically just figure how tall and wide you have room for in the furnace, then use a wood dowel to where it would give you the target wall thickness.} 3.) Before you leave it to cure, lightly tap the sides of the container to settle the mixture, and bring whatever bubbles there may be to the top. Just a quick suggestion on materials. 1/4 part Quickcrete, 1/4 part Firebrick and 1/2 part clumping type cat litter (finely crushed)...ie: consistency just slightly coarser than powdered sugar. The clumping kind is important because it will give you the sand/clay content in roughly equal amounts. Plaster works to an extent but will only hold up for a few casting cycles, before the Crucible fails and you need to make a replacement. **Before ppl start giggling about using kitty litter, I use it on it's own/sometimes mixed with powdered aluminum (for nosecone and multi-stage delays) as plugs for model rocket engines/fireworks and it holds up very well to heat.

Glen, spend the 20bucks and buy a cheap graphite crucible. It's not worth an UH OH using home made shit. Trust me man, I pour bronze very regularly and one disaster is all it takes to change your life forever.

Formulas fire brick clay and graphite and cilica carbide. Older peeps just use fire clay or red clay and grapgite with no sand

3 likes if I could. I watched it 3 times in a row. Now I’m gonna try it. Thanks!

So, you have your grog already, and sand. MacGyver needs a lot of graphite...easy, break those old batteries and you have it. The problem is how much of the mixes is needed. Don't use water, used glass water instead.

What is the temperature needed to dry and cook a graphite crucible?

I appreciate the MacGuyver route. I've been doing the same since around May myself. Might as well have fun with it. I DON'T like to shop. Anyway, I'll share some ideas. I see some have been mentioned already, but I'll try to flesh them out some: I'm just beginning to mess with graphite, but it seems to be working so far. You can reduction burn some pencils (wrap them up and make charcoal out of them) in the forge, then burn up the charcoal. The graphite should be sitting in the bottom largely intact after the charcoal and binder is burned up. If you're willing to sacrifice a coffee grinder, it'll help save a lot of time and material. Incorporate at least enough to blacken your mix. Any amount should help. You can get clay from your yard if you dig down a few feet most likely. Just throw it out if it's red. The rust will flux the mix prematurely and cause it to fail. I've been using a fine mesh laundry bag to filter my clay a few times and then switch over to an old high thread count pillow case. Learning how to make it has really opened up a lot of possibilities for me. It's 15,000 year old technology and it's inherently sustainable, and cheap. Everyone is right about the portland cement. Plaster of paris has the same problems. Both got popular due to DIY coffee can forges, but they aren't any good for consistent high temperatures. Someone mentioned burning calcium hydroxide into calcium oxide, but calcium alone isn't the best readily available refractory metal. I wouldn't seek it out unless it's bound to something better... i.e. calcium aluminate... and... pyroxenes? Christ this is complicated... Adding a little sodium silicate, like a spoonful may help with binding, but I wouldn't use it as a primary binder as has been suggested below. I forget why I abandoned that route. My forge is mostly held together with it, but I had to tweak the composition a whole lot to stop the big cracks. Anyway, You can make it with lye (100% lye crystal drain opener) and dessicant packets. Just do your best to get a neutral mix before adding it. I forget the exact ratios, but I'm thinking 3 parts silica gel dessicant, 2 parts lye, and 5 parts water. Use protection. Be patient with it. An overly alkaline mix will leech salt and wreck your skin. The best thing I did for my forge was to reinforce it with steel. I used allealed steel wire twisted and woven for tension as close to the middle of my walls as I could get it and reinforced the outside and weak-points, like the lid and fuel ports with stainless steel mesh from dirt cheap loose strainers I found at Wal-Mart. I forget what they were called or what they're for, but $4 worth gave me more than enough for the whole thing. They look like little mesh bags and come with zip ties. I'm not sure if the same method would be helpful on the scale of a crucible as the reinforcement would get a lot hotter, but it's worth trying. Anyway, for more exotic refractory materials I had to brush up on basic chemistry. Cody's Lab helped, as did Wikipedia. I searched primarily for "refractory" and "'insert metal here' oxide" and read through "production" and "application" for several metals. Eventually it all came together. You can make magnesium carbonate out of epsom salts and washing soda (a really simple precipitate reaction you can do on your stove) and then dry it out and burn it down at, I think at least 2000 F for magnesium oxide, which is essentially fireproof. I'm still working on an easy method for alumina, which is the active ingredient in your fire brick. So far I've just been adding scrap aluminum foil to my clay sluice until it starts breaking down and then baking and grinding it. I'm not sure it's working. I just threw some in vinegar and HP to try to get some aluminum acetate I can hopefully burn down... but it's not too expensive to buy... and it's about 30-60% of your firebrick. Grogging with ground up borosilicate (pyrex) and porcelain (white ceramic cookware) might help. Grahite, Dehydrated Magnesia, and Alumina are the most accessible refractory materials to do all this MagGuyver style I think. I'm working on chromium and molybdenum, but it's a dangerous quest, especially the chromium... If I remember right, Chromium III turns to Chromium VI, which murders your DNA, at 1800 F or more... Probably best not to mess with it. it might pay to set up an electrolysis rig (car battery and a bucket) and invest in some hydrochloric (muriatic) acid, nitric acid, lye, lyme, washing soda, epsom salt, vinegar, hydrogen peroxide, and so on and so forth to tailor your electrolytes. Once you've got the ability to inject massive amounts of energy into compromised minerals, you can pretty much make anything. It's all about making hydrogen and oxygen do what you want them to do... I've found... over several long and confusing months...

Always use sprat cooking oil to stop sticking. Tin sheds, cement wipes off. Double the cement.

SO EXCITING

So, Crushed up clay no sand & your fire brick crushed up mix worked ? Is that not the second one it's clay & concrete ? I know that concrete dissolve into powder from water, but I'm super curious to see Clay & fire brick mix alone to see if that will make a paste someday, maybe I'll experiment I hope I don't drastically mess up !.....

Magnesium and plaster for a crucible. Add steel wool for longer use?

Grease the cup and use a greased tapered piece of dowel. Also, take the dowel out as soon as you can. The cenment mixture will shrink against the wood and crack.

You have to preheat it in the regular oven for a few hours before you introduce it to a high heat

ممتاز ... روعه انت عبقري منذ فترة طويله وانا ابحث عن طريقه لصنع بوتقه لصهر النحاس بمواد متوفره وغير مكلفه ولم اجد لا بالكوكل ولا باليوتيوب حتى تعبت من البحث واجريت عدة تجارب عليها فلم تنجح عندي علما انني بحاجه ماسه لها لكي اصهر بها النحاس وكل شيء متوفر لدي من فرن وعده إلا البوتقه لكنني الآن تعلمتها فشكرا جزيلا لك ايها العبقري

I think you need to apply some pressure to compress the crucible during the drying process, so it compress the compound... Also, instead of cement, try putting graphite into the mixture, along with the ceramic clay. Just a thought

Thank you sir

Definitely subscribed

Notwithstanding the fact that this is absolutely ridiculous but if you had the right ingredients you're still making it about 10 times wetter than you would want

Plastic mold. 3 parts of sand, 1 part of cement. Mix it up. Do not pulverize the fire brick, little rocks maybe, put them with cement and sand. Add water and put on mold. Don't use the wood, use a piece steel (pubricate wuth vaseline). When it is a little hard spray water every one hour. At the other day open the mold and spray with water a couple of times. Let dry completely. Concrete takes up to 2 weeks to dry in that size. Then try it out

Im looking for a crucible for case hardening rail road spike knives. Having trouble find one of proper dimensions.

Hello Glen, I had an idea that may work. Get a chunk of raw clay and try to form it to a shape of the crucible, then fire it in your forge. Fired clay things like a brick can withstand serious heat if water doesn't get trapped inside the clay. I think for melting copper it will be fine.

All you need is clay, hard wood ashes and a little sand. The wood not only swelled it held moisture. You should have wrapped the metal in plastic wrap.

when we sement something after it started hardening we put a water hose on it and keep it wet for 2 or 3 days,if u do that your sement will be like steel,more water the better results you get.in my house any part of the walls that i forgot to give water is like sand and u can carve it with your fingers.sorry for my poor english i hope i was a little help to some people

You have to crush the fabric to 2 to3 kind of material one parts have to be powder another parts have to be on the rough and the third parts have to be rougher and you must add sugar powder and citric acid to the mix that makes it combined together that’s how they make the five bricks

Cement hold in liquid and allows cracks so use plaster

I hate to be a party pooper but why didn't you just use a masonry bit to drill a hole in the brick as deep as you need, then trim it with a masonry blade to the size you need.

Why not just cut the fire brick to the shape of a crucible

You might try luting. In the 18th century and before, poor people made livings recycling, and one of the things gathered was bone. The bones were calcined to make luting, which was a sort of cement used in furnaces. It is possible that a luting/clay mixture might work for this. I just tried looking it up, but the word has been taken over by dentistry for other putty-like materials for dental procedures. Books of 19th century industrial recipes might have it.

Your projects are interesting, thank you for the time you take to make these videos. I like your anvil, and have seen them elsewhere but always in clips, never in "person." Where did you get it please, and what was the cost? Thanks again.

hi, sincerely talking was this time resisting over time or how much can they resist_=?

Recrush it up including the cup...which is ceramic.

Never use cement in high temp. Reasonably got solution for crucibles would be -clay, fire brick and liquid glass stil won't gonna last long but for small crucibles its quite good.

Check ur cement grade as well..add lime

Maybe a ball-mill will powder it up fine enough to make a crucible.

Trail and error the best way to learn.

Состав для тигля. 1 часть каолина, 1 часть графита, 1 часть карбида кремния, 0.5 части пластичной огнеупорной глины.

Just curious if all I have is three holed clay brick / I assume it's called red clay fire brick, if I crash that up with my hammer, will that make a paste with water alone that's capable of holding my bricks together for forging ???? I'm learning & do not know anything about this stuff....

Think about crushing up some pencil lead (graphite) and add to the mix

I have an idea: what if you blend the firebrick powder with something like clay? Gray clay like from a creek bed?

very good

Waxing the FORM woulda changed things "going south"... .... my backseat perspective flashed me. I am merely a messenger. My past endeavors in crucible/kiln werks has SODIUM SILCATE compounds.

You should use clay instead of cement and add a decent portion of graphite

Ha ha, That was awesome, you were born 1000 years too late just like me. Thanks!